She asked: "Is your evidence on oath that you actually saw him, in your presence, mark that black line?"

"Yes," Mr Rees replied.

"The note of your evidence about that black line is that was where he had inspected the water?" said Ms Evans.

"Yes," added Mr Rees.

"Where he had found the water?" she asked.

"Yes. He had been in and found the water at that level," Mr Rees said.

Sludge and dirt

But she then read a section of Mr Rees's police statement where he had told officers: "I didn't see Malcolm draw these markings but they were definitely on the plan."

Another section read: "Because he was able to show where he thought the water level was, I would imagine that Malcolm had been in there?"

Ms Evans said: "There's a world of difference between giving evidence that someone told you 'I have been in there' and what you did, repeatedly, to say to the police that you 'assumed' and 'I imagined'."

Mr Rees replied: "I stand by what I say. Mr Fyfield did tell me he had been in there to inspect the water."

Ms Evans then asked: "Are you definitely saying that Mr Fyfield told you that he had been in there to see that location?"

"Yes," he replied.

The court has heard that Mr Fyfield was one of seven men working in the mine at the time of the explosion and survived after he crawled out through sludge and dirt.